I use OPNsense-15.1.9-cdrom-amd64.iso, I will be able to test it on a real machine not a VM. Will also try a compete reboot of my own host in case of. Using OPNsense-15.1.8-cdrom-amd64.iso brings absolutely no troubles.

Confirmed, the installation went fine at 1G. Thank you franco! I would suspect something that reserves RAM or something that uses more RAM (file decompression ? Archive size ?) at first glance. Has the kernel configuration changed between versions?

cpdup(1) may be allocating too much RAM or it is part of the new async write we have pushed into the BSD installer. None of those issues are unsolvable, even though they shouldn't materialise in this out of memory kill sort of way. We'll find out why, no worries.

I just tested this with the upcoming 15.1.11 images: cpdup(1) has been replaced by the traditional tar(1) utility and now installs with only 512MB of RAM, but not all files land on the disk. I expect this is a serious issue without tar(1) noticing... Might as well have something to do with the images being larger installations now. Will debug this further...

It seems so, but I really do not know what is happening. It looks like low RAM is the "culprit", but this seems like kernel pipe magic to be honest. At least cpdup(1) realised there was something going wrong, bailing accordingly.As long as you have 1GB of RAM you won't have to worry.

Last update on this, yeah, so it turns out you need RAM to copy a file. When doing batch copies, you need the size of the directory in actual RAM, amounting to hundreds of MB in the case of /usr/local. None of the UNIX tools seem to care and silently fail, which makes me go full circle on this issue and put cpdup back, because that's the only one that actually fails in said case.

Workarounds exist that require swap partitions to be written and activated prior to install, but:

(a) the swap could still be too small, and(b) some systems have CF cards where there is no point in adding a swap partition to the installation medium.

Remember, we are talking about a live CD or memstick here and that is why we don't own a swap partition.

Lastly, the only time we see these issues is when users try OPNsense in a VM, assigining too little memory to it.